Field of the Invention
The prevent invention relates to an electrophotographic photosensitive member comprising an aluminum substrate having an aluminum oxide film at its surface and a photosensitive layer formed thereon.
Heretofore, inorganic photosensitive materials such as selenium, cadmium sulfide, zinc oxide and amorphous silicon have been used for electrophotographic photosensitive members. However, these materials have problems of toxicity, inferior moisture resistance as photosensitive materials and high production costs.
In recent years, organic photosensitive members employing organic photoconductive materials have been widely used instead of the inorganic photosensitive members, since the organic photosensitive members have advantages that non-polluting materials can readily be selected and the production costs are low, and from the viewpoint of characteristics, a high photosensitivity and a high printing resistance are obtained.
Most organic photosensitive members placed in practical use are so-called laminated photosensitive members, each having at least a carrier generation layer and a carrier transport layer formed on an aluminum substrate. Such layers are usually laminated on the aluminum substrate by a dip coating method or a ring coating method.
To prevent the generation of a phenomenon such as black spots or background fogging due to local charging deficiency of the photosensitive member, various measures have been made for carrier injection from aluminum, for example, a method wherein a polyamide resin is coated as a blocking layer (intermediate layer) on an aluminum substrate as disclosed in JP-A-58-30757, and a method wherein an aluminum substrate is treated by anodization to form an alumite layer as disclosed in JP-B-7-27264.
The aluminum material used for such a photosensitive member is usually produced and processed by extrusion molding into a desired shape. However, by the progress of colored documents in business field in recent years, it has been difficult to disregard the influence of uneven density by dimensional inaccuracy in the processing of the aluminum substrate, whereby accuracy in processing has been demanded.
Further, as an organic photosensitive material formed on the substrate, a positive-charging type material which exhibits less ozone generation is favorable from the viewpoint of office environment, and a photosensitive material having phthalocyanine type photoconductive particles dispersed in a binder resin has been studied.